1. Field of the Invention
The present invention is related to a method and a system for processing a stereoscopic image stream, and more particularly, to a method and a system for reconstructing a stereoscopic image stream from quincunx sampled frames.
2. Description of the Prior Art
Three-dimensional (3D) display technology provides more vivid visual experiences than traditional two-dimensional (2D) display technology. In general, the stereoscopic image processing involves two camera systems in which two different images or videos are taken from slightly different camera angles and locations. Techniques to artificially create a perception of depth on a 2D surface include the use of presenting different images to the left and right eyes of the viewer. In such frame sequential 3D display system, a sequence of alternating frames wherein each successive frame carries the image meant for one or the other eye is presented to each eye using shutter glasses having a left-eye lens and a right-eye lens, each of which may be made from electronically controllable liquid crystal assemblies. The lenses are configured to be alternatively switched on and off in sync with the alternating frames such that the right eye only views the right-eye images and the left eye only views the left-eye images. The two series of images are combined by the brain in such a way to perceive depth.
Most recently released 3D high-definition televisions (HDTVs) operate according to the frame sequential 3D display method described above. However, this doesn't mean that the input signal to the 3D HDTV has to be in a frame-sequential format. Instead, many 3D HDTVs can process signals in a variety of different formats and perform on-the-fly conversion of the incoming video signal into a frame sequential format. While frame-sequential 3D is part of the blu-ray 3D specification, the video data in a side-by-side format is often preferred when it comes to airing 3D content over cable/air.
FIGS. 1A-1D are diagrams illustrating a prior art method for encoding 3D images. FIG. 1A depicts an original left-eye frame L and an original right-eye frame R of the same full resolution, such as 1920×1080. In FIG. 1B, the left-eye frame L and the right-eye frame R are processed by quincunx sampling, which, as well-known to those skilled in the art, is a sampling method by which sampling of odd pixels alternates with sampling of even pixels for consecutive rows, such that the sampled pixels form a checkerboard pattern, thereby resulting in a sampled left-eye frame L′ and a sampled right-eye frame R′. In FIG. 1C, the remaining pixels are slid in the horizontal direction for providing a down-scaled left-eye frame L″ (consisting of pixels marked by diagonal stripes which go top right to bottom left) with a resolution of 960×1080 and a down-scaled right-eye frame R″ (consisting of pixels marked by diagonal stripes which go top left to bottom right) with a resolution of 960×1080. In FIG. 1D, the down-scaled left-eye frame L″ and the down-scaled right-eye frame R″ are placed side-by-side, thereby forming the side-by-side frame SBS.
Since the side-by-side frame SBS contains half the pixels compared to those in the original left-eye frame L and the original right-eye frame R, it can be transmitted more efficiently. However, the missing pixels that have been lost by quincunx sampling need to be reconstructed for playback, normally according to several known interpolation algorithms. Examples of such algorithms include nearest neighbor interpolation which directly applies data from the neighboring pixels to recreate the missing pixel. Unfortunately, such an algorithm produces diagonal line artifacts which result in a deteriorated reconstructed image. There is thus a need for a method capable of generating a stereoscopic image stream with better quality by reconstructing missing pixels of quincunx sampled frames.